Improve how we set page titles

[reefdog]

We could use a bit of DRYing up how we set document.title throughout the site. All over the place you'll see things like:

useEffect(() => {
	document.title = 'Some page name - Philanthropy Data Commons';

	return () => {
		document.title = 'Philanthropy Data Commons';
	};
}, []);

This is using useEffect (the safe place to make DOM edits) to set the document.title on page/component load, then returning an unmount method to restore its former glory.

This should really be something more like setTitle('Some page name') and then resetTitle() at the end.